This paper presents an overview of the posters presented in the sessions 1, 6 and 9 of the Watermatex 2000 conference. The first session focused on the development of new models in different areas of environmental technology, e.g. wastewater, ground pollution, sewers, etc. The sixth session dealt with integrated urban wastewater systems. Session 9 focused on the application of neural network modeling and principal component analysis in time series analysis. Rewarded posters are mentioned and selected for full paper publication in this issue of Wat. Sci. Tech.